Voltage and Current divider arrangements are the common in electronic circuits. Before selecting the value of resistors, it is necessary to calculate the voltage and current from the output of a resistor chain. So that the circuit will function properly. Here is a simple but useful tip to calculate the voltage and current from resistor chains.

**Voltage divider**

By selecting appropriate values of resistors in the divider, it is easy to obtain a fraction of the input voltage. See the voltage divider diagram. The value of the output voltage V Out from the divider R1-R2 will be

**V Out = V In x R2 / R1+R2**

Suppose we need **5 volts output** from a 15 volt power supply.Then we should use the value of R1 twice that of R2. Value of 2K for R1 and 1K for R2 will do the trick

**V Out = V in x R2/R1+R2 = 15 X 1000 /2000+1000 = 5 Volt**

If the power supply is 12 volts, you will get 4 Volts from the same divider.

If we use 200 ohms for R1 and 100 ohms for R2, same output voltage will be obtained, but current will be more.

## Voltage and Current divider

**Current divider**

By selecting appropriate values of resistors in the divider, it is easy to obtain required output current from the divider.

**I Out = I In x R1/R1+R2**

Suppose you need a current of 5 mA from a 15 mA input current, you should select the value of R2 twice that of R1. If you select 1 Ohm for R1 and 2 Ohms for R2, then the output current will be 5 mA

**I Out = 15mA xR1/R1+R2 = 5 mA**

If you use 10 Ohms for R1 and 20 Ohms for R2, same output current of 5 mA will be produced but increased voltage drop will be the result.